1. Field of the Invention
The present invention relates to a device for counting and determining the direction of conveyed material hanging on hangers provided with hanger hooks, particularly articles of clothing, in which the hanger hooks each have a stem that passes through a light barrier connected to a counting and evaluating unit.
2. Description of the Related Art
Such a device is known from Federal Republic of Germany A-33 15 597. In that counting device, the transmitter and the receiver of the light barrier are arranged above and below the free end of the hook present on the hanger and thus detect the tip of the hook passing by the light barrier.
The known counting device has various disadvantages. For example, the light barrier is directed to the tip of the hook, therefore, the hook of the hanger must have a well-defined shape in order for it to be reliably detected. If the tip of the hook is too short, the hanger is not detected. If the hooks of two hangers hanging one behind the other on the trolley cross each other, and if the point of intersection lies at the tip of the hook, the light barrier detects only one hanger, and an erroneous count results. Oblique hangers can also not be reliably detected by the light barrier and it is not out of the question that a hanger hook which is swinging during counting will lie just outside the beam of light upon passing the light barrier. Also, because the tip of the hanger hook is detected, the loading side of the trolley is dictated by the location of the light barrier.
Federal Republic of Germany A-29 22 471 discloses a human passer-by counting device in which a light barrier is used which has at least two receivers that are spaced apart vertically in a plane and include two round sensors that operate independent of each other. The arrangement of transmitters and receivers disclosed therein assures that the light barrier detects only persons who pass through it and not other forms of life. Furthermore, an indication is given as to the direction of passage. The light barrier must be so installed that, in principle, in all cases only one person can pass through the light barrier. Two people who are walking together alongside or closely behind each other could not be detected by the prior art device as two people. The use of such a known light barrier device for counting continuously conveyed hangers which lie back to back is not possible.
Republic of Germany A-30 45 657 discloses a counting device for counting structural parts fastened spaced apart from each other on a belt. Here, also, only individual structural elements which pass through the light barrier are counted. Structural elements which lie one on top of the other or closely alongside each other cannot be detected as being more than one.